In resection endoscope with a high frequency-energized cutting electrode, the electrode is commonly moved in the longitudinal direction of the instrument by means of an actuating mechanism on the endoscope structure into the desired cutting position and, particularly in a urological resectoscope, is drawn in a particular direction during the cutting process. A high frequency power generator is connected to the electrode through a switch by which the operator can control the supply of high frequency current. The current can be switched directly or by indirect control of the HF generator. Commonly, the switch is constructed as a foot switch positioned within the reach of the operator.
Many different structural forms of carriers and actuators are known for such instruments, but commonly two handles are arranged to be mutually movable in the longitudinal direction of the instrument, one being moved with the thumb and the other with the index finger. In most cases, the movement occurs in one direction against the force of a spring and automatically, with the aid of the spring, in the other direction. However, carriers or actuators which are moved by different structures such as by means of a rack and pinion drive can be used.
One known resectoscope of the type generally referred to above has the HF switch on the carrier. In this construction, the switch is arranged so that it is operated with a different finger independently of the operation of the actuating device.
A disadvantage of the known resection endoscopes is the fact that the actuation of that portion of the carrier which causes movement of the electrode and the actuation of the power switch are accomplished independently and, thus, twice as much attention is required from the operator in order to properly synchronize the carrier actuation and the switch actuation in a desired manner so that the switch is closed only during actuation of the carrier in the cutting direction. As will be recognized, the term "closed" refers to a switch condition in which the power circuit is complete, allowing current to flow to the electrode. Incorrect operation can occur for various reasons such as the result of a shock or startled reaction to unforeseen events or simply as the result of inattention. Such incorrect operation can lead, for example, to moving the cutting electrode in the wrong direction with the HF current switched on. This can result in serious injuries to the patient.